A: Kristina, all parents want to know whether their baby is “normal,” and it’s natural to compare your baby to other babies of the same age. But you’ll notice that there’s not just one normal size—babies come in different shapes and sizes.

Your baby’s size is determined by many different factors including her heredity (how big you and her father were as babies), health, nutrition and activity level. To follow your baby’s growth, the doctor will weigh and measure your baby at each well-baby visit and plot your baby’s growth on a chart. Be sure to ask the doctor to show you and explain your daughter’s growth chart. Signs that your baby’s growth is healthy and normal include: her height and weight fall within the range that is normal for her age, her weight is in the right range for her height and she continues to grow at a healthy rate over time, along the growth curve.

At 15 months, as at any age, there is a wide range of height and weight that is considered normal. Although the median height—the 50th percentile, at which half of children are taller and half of children are shorter —is 30½ inches (77 centimeters), 90 percent of children fall within the normal range of 28 to 32 inches tall. And although the median weight is 23 pounds (10.5 kilograms), 90 percent of children fall within the normal range of 19 to 27 pounds (8.5 to10.5 kilograms). In fact, over the second year of life, babies don’t grow quite as fast as they did in their first year. But bigger babies tend to grow a little faster and smaller babies tend to grow a little slower, so the range of what’s considered normal gets even wider. If you are interested in viewing the standard growth charts, visit the Centers for Disease Control website at www.cdc.gov/growthcharts/.

Children who are large for their age may be mistaken for older children, and people may mistakenly expect them to demonstrate skills and behavior for which they are not developmentally ready. At 15 months of age, babies typically have a vocabulary of three to six words; they can follow simple instructions (“Show me your tummy”); they can feed themselves with their fingers, a spoon and a cup; and they are starting to walk and climb. But just as there is a normal range of sizes for children, there is also a normal range of development for children at any age. Some 15-month-old babies are doing these things and others are not yet ready. If relatives, friends or childcare providers have unrealistic expectations of your daughter, you can gently remind them that she is only 15 months old. If you have questions about whether your daughter’s development is normal for her age, be sure to talk with her doctor.

Finally, even though your daughter is a toddler, it’s never too young to develop healthy habits and healthy attitudes about her body size. Make sure she eats a variety of nutritious foods, and that she has the opportunity for active play each day. And help her feel proud of how healthy and strong her body is.